In mobile devices such as smart phones, which have been rapidly spread in recent years, a touch screen panel is generally provided to implement a variety of functions. In the past, a low-cost resistive touch screen was widely used. However, the resistive touch screen may cause deterioration of the quality of the display. Recently, therefore, the capacitive touch screen is widely used. As the touch screen panel is generally used in a mobile device, there is a need to develop a technology for more stably detecting or sensing a touch input in a noisy environment. In other words, to improve the sensitivity of a signal in the touch screen, efficient cancellation of the noise is required.
FIG. 1 illustrates an integrator circuit in which an inverting integrator circuit and a non-inverting integrator circuit are coupled for cancellation of noise according to the related art.
Referring to FIG. 1, a technique for cancelling noise may employ two integrators (i.e., a first integrator and a second integrator) in which the first integrator or the second integrator are used according to a clock signal CLK. This method for cancelling noise is disclosed in U.S. Patent Publication No. 2011-0273400, so a detailed description thereof will be omitted.
However, in the technique for cancelling noise as illustrated in FIG. 1, to accumulate charges in two feedback capacitors Cfb1 and Cfb2, separate operational amplifiers OP Amp 1 and OP Amp2 for their associated capacitors Cfb1 and Cfb2 are required. Therefore, since charges should be accumulated during a plurality of signal cycles, in order to extend the dynamic range, capacitances of the capacitors Cfb1 and Cfb2 should be increased, which is undesirable.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.